J Am Coll Cardiol. 2013;61(5):545-550

　　

 

Angela Hoye MB ChB， PhD， MRCP  英国Hull York医学院

 

　　The percutaneous approach to opening chronic total coronary occlusions (CTO) has undergone huge changes in recent years. This transformation has been driven by concurrent advances in technologies such as the introduction of new specialist guidewires， together with the uptake of new techniques primarily introduced by innovative ideas from Japanese colleagues. The success rates of percutaneous recanalisation (PCI) have significantly improved， however this would have been of only limited value without the introduction of drug-eluting stents (DES). The treatment of CTOs with bare metal stents was hampered by a significant rate of restenosis， with re-occlusion seen in up to 20%. More recently though， both randomised study evaluation and registry data demonstrate the efficacy of DESs in patients treated for CTO.

　　With the improvement in success rates and the development of “expert” CTO services， an increasing proportion of patients with a CTO are being offered PCI in preference to bypass surgery or a more conservative approach with medical therapy. However， there is a real lack of understanding of the long-term efficacy of this therapy. In the current issue of JACC， Valenti and colleagues present interesting new information gained from their Italian CTO registry. Of more than 1，000 patients， successful PCI (as defined by a final diameter stenosis <30% with TIMI grade 3 flow， without death， Q-wave myocardial infarction or emergency bypass surgery) was achieved in 77%. This “real world” registry reflects contemporary practice with the majority of patients having multivessel disease (triple vessel disease in 49%). The authors have an angiographic follow-up rate of 82% performed at 6-9 months and found a restenosis rate of 20%， including re-occlusion in 7.5%. The independent predictors of reocclusion were a PCI strategy that used subintimal tracking and re-entry (odds ratio 29.5; p<0.001) and everolimus-eluting stents (odds ratio 0.22; p=0.001).

　　The subintimal tracking and re-entry (STAR) technique was utilised in only a minority (4%)， but with relatively poor results - re-occlusion in 57%. In contemporary practice， this technique is only used as a “last resort”. A hydrophilic wire is formed into a small “loop” which is advanced through the sub-intimal space. At a point of bifurcation， further pushing on the loop will (usually) force it into the true lumen of one or other branches. However， such a long length of sub-intimal tracking will impair flow into most or all side branches such that the technique has been used predominantly in the right coronary artery with relatively fewer important branches. The long length will also necessitate a potentially long length of stented segment which will increase the potential for restenosis. Godino et al have recently described results of 74 patients treated with “guided-STAR” as compared to 281 patients treated with conventional antegrade recanalisation， and demonstrated signficantly higher restenosis in the guided-STAR cohort (54% versus 30%) reinforcing the data to suggest that， where possible， other recanalization strategies are preferable.

　　The STAR technique must be differentiated from other CTO strategies that incorporate a sub-intimal path， indeed IVUS studies suggest that it is common for the guidewire to pass subintimal for at least part of its course during CTO PCI. [7] A limited sub-intimal path is integral in contemporary CTO PCI practice especially when the occlusion length is relatively long. The CART and reverse-CART techniques rely on enlarging the sub-intimal space to facilitate wire passage from true to false and back into true lumen. [8] The Stingray re-entry system from Bridgepoint (recently acquired by Boston Scientific corp) utilises a flat balloon that is positioned within the sub-intimal space just distal to the occluded segment， the true vessel lumen is “punctured” with a dedicated penetrative wire. With this system， the sub-intimal tracking is limited and preliminary results are favourable in terms of procedural success. [9] All of these procedures involve stenting of the subintimal space， and there is a paucity of data as to the effect that this has on subsequent restenosis. A high rate of restenosis and reocclusion is clearly evident for the STAR technique but it is not known whether this is due to stenting of the subintimal space or is simply a reflection of the long length of stented segment. An additional problem is that the diameter of stent used in CTOs is often undersized as the vessel is chronically underfilled and does not respond to intra-coronary nitrates. The use of IVUS， which might help to optimise stent implantation， is low in the majority of countries but should be considered in all cases where the stented length is long.

　　The demonstration of a significantly lower rate of re-occlusion with everolimus-eluting stents (EES) as compared with first generation drug-eluting stents (sirolimus- and paclitaxel-eluting stents) is consistent with results seen in published randomised data. The present study is not randomised and does not differentiate the results of sirolimus-eluting versus paclitaxel-eluting stents， however the difference in favour of EES was evident on analysis of a propensity-matched subset of 588 patients. It will be interesting to see whether future work will demonstrate further improvement in outcomes when newer generation DESs are used. Re-occlusion may occur in the absence of symptoms and so， where possible， future studies should incorporate follow-up angiography.

　　In the present study， 54% patients were treated with >40mm stent and it is well recognized that the treatment of complex CTOs may require implantation of a “full metal jacket” within the coronary. This is not ideal as it may impair endothelial function recovery and preclude the option of bypass surgery at a later date; the continued development of completely absorbable stents may， in the future， play a key role.

　　One additional finding of the study that should be mentioned is that complete revascularisation predicted a lower rate of cardiac death (hazard ratio of 0.48). This is consistent with previous data published from the same group and emphasizes that the ability to undertake complete revascularization should be taken into account when assessing the relative merits of PCI versus bypass surgery in patients with multivessel disease including a CTO.

　　The study by Valenti et al. emphasizes that PCI for CTOs continues to be an evolving field within interventional cardiology with more research needed to further improve outcomes in this challenging patient population. The results are encouraging that both the short- and long-term success rates for patients treated with PCI for a complete coronary CTO continue to improve.

 

　　中文摘要

 

　　随着CTO专用导丝、新型技术和DES的引入，CTO PCI的成功率显著提高。更多CTO患者接受PCI，而不是旁路手术或药物保守治疗。然而，人们对PCI治疗CTO的长期效果知之甚少。

　　本期JACC中，Valenti等的注册研究反映出真实世界CTO患者多为多支血管病变，其中三支病变占49%。6～9个月随访时，82%患者复查血管造影。STAR技术仅用于4%的患者，但再狭窄率达到57%。在临床实践中，STAR技术仅作为最后的手段使用。长距离内膜下循径可损伤分支血流，也导致延长的支架区域，使再狭窄风险增高。但必须区分STAR技术和其他需要内膜下循径的CTO PCI技术。事实上，有限的内膜下循径是当代CTO PCI实践的组成部分，如正向和逆向CART技术。内膜下循径对再狭窄影响的临床数据很少。

　　第二代EES较第一代DES显著减少再闭塞的结果与其他随机试验结果一致。该研究中，倾向配对的588例患者数据证实EES的这种优势。再闭塞可能无临床症状，未来研究应尽可能复查血管造影。

　　该研究中，54%患者置入> 40 mm的支架。这不是一种理想状态，可能损害内皮功能修复，也可能使旁路手术成为不可能。完全可吸收支架的开发可能对CTO有重要意义。

　　该研究还显示，完全血运重建预测较低的心因性死亡（风险比0.48）。因此，在评价PCI或旁路手术对多支血管病变包括CTO的利弊时，应重视完全血运重建的可行性。

　　Valenti等的这项研究强调CTO的PCI在不断发展，需要更多研究以改善患者预后。